JP2003258435A - Sheet material for wiring board and multilayered wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet material for wiring board that is composed of an electrical insulating resin and can form the surface of an insulating layer formed by thermocompression bonding the sheet material to the wiring pattern forming surface of a resin substrate having a formed wiring pattern in a flat surface. <P>SOLUTION: The electrical insulating resin constituting the sheet material 10 thermocompression bonded to the wiring pattern forming surface of the resin substrate having the formed wiring pattern is composed of a resin which is softened or fluidized at a thermocompression bonding temperature. The sheet material 10 comprises a thermocompression bonding film layer 14 one surface of which is thermocompression bonded to the wiring pattern forming surface of the resin substrate, and a non-thermocompression bonded film layer 12 which is bonded to the other surface of the film layer 14 and composed of a resin having a softening temperature or fluidizing temperature higher than the thermocompression bonding temperature. The film layer 12 has a glass transition point temperature higher than the thermocompression bonding temperature or has no glass transition point. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board sheet material and a multilayer wiring board, and more specifically, it is composed of an electrically insulating resin which is thermocompression bonded to a wiring pattern forming surface of a resin substrate on which a wiring pattern is formed. Sheet material for wiring board,
And a multilayer wiring board in which a plurality of wiring patterns are laminated in multiple layers with an electrically insulating resin layer interposed therebetween.

[0002]

2. Description of the Related Art As a multilayer substrate for a semiconductor device used in a semiconductor device, there is a multilayer wiring substrate for a semiconductor device shown in FIG. 6 (hereinafter sometimes simply referred to as a multilayer wiring substrate). The multilayer wiring board shown in FIG. 6 is a resin board 1 as a core board.
Through hole vias 110, 110 ...
The upper layer portion 1 formed on both sides of the resin substrate 102 by
The wiring patterns 104, 104, ... Formed on each of the lower layer portion 106b and the lower layer portion 106b are electrically connected.
Further, also in each of the upper layer portion 106a and the lower layer portion 106b, the electrical connection of the wiring patterns 104, 104, ... Formed on both surfaces of the resin insulating layer is formed by penetrating each insulating layer. Made by vias 118, 118 ... Further, on the uppermost layer of the upper layer portion 106a, the electrode terminals 122, 122, ...
., Which are electrically connected to the pads 124, 124 ..
Except for 24, ..., It is covered with the solder resist 126. On the other hand, pads 130, 130 ... On which the solder balls 128, 128 as external connection terminals are mounted are formed on the lowermost layer of the lower layer portion 106b, and the lower surface of the lowermost layer is the pads 130, 130. Except for ..., It is covered with the solder resist 132. A resin or a conductive resin is filled in the through hole via 110 of the multilayer wiring board shown in FIG.

The multilayer wiring board shown in FIG. 6 can be manufactured by the build-up method shown in FIG. According to this build-up method, the upper layer portion 116a and the lower layer portion 116 shown in FIG.
It is formed simultaneously with b. Therefore, in FIG. 7, the forming process of the upper layer portion 116a is shown, and the forming process of the lower layer portion 116b is omitted. In the build-up method shown in FIG.
The wiring board sheet material 200 shown in (a) is used. This wiring board sheet material 200 (hereinafter referred to as sheet material 20
0) is a resin film 204 made of thermocompression bonding resin such as epoxy resin formed on one side of the PET film layer 202 made of polyethylene terephthalate (PET) as a supporting film layer. is there. As shown in FIGS. 7A and 7B, the surface of the resin layer 204 of the sheet material 200 is the wiring pattern 10.
Are superposed so as to abut on the wiring pattern forming surface of the resin substrate 102 as the core substrate on which 4, 104. Further, while pressing the sheet material 200 against the resin substrate 102 with a predetermined force, the sheet material 200 is heated to a temperature at which the thermocompression-bonding resin forming the resin layer 204 of the sheet material 200 is softened or fluidized, and the two are thermocompression bonded [FIG. 7 (b)]. The PET film layer 202 of the sheet material 200 is then peeled off [Fig. 7
(C)]. This is because the PET forming the PET film layer 202 is softened and the shape of the PET film layer 202 is deformed when the sheet material 200 is thermocompression-bonded to the resin substrate 102. After that, the wiring pattern 104 and the via 118 are formed on the exposed surface of the exposed resin layer 204 by a known method.
Are formed [FIG. 7 (d)]. 7 (a) to 7 (d)
By repeating the above operation, the multilayer wiring board shown in FIG. 6 can be obtained.

[0004]

By using the sheet material 200 shown in FIG. 7A, the resin layer 204 can be easily formed on the wiring pattern forming surface of the resin substrate 102. However, when the PET film layer 202 is peeled off after the sheet material 200 is thermocompression-bonded to the resin substrate 102, the exposed surface of the resin layer 204 is, as shown in FIG.
.. corresponding to the wiring patterns 104, 104 ... In this way, the resin substrate 102
When the exposed surface of the resin layer 204 formed on the wiring pattern forming surface of is formed into an uneven surface, the wiring patterns 104 formed on the exposed surface of the resin layer 204 are
It is formed following the exposed surface shape of 04. Therefore, the exposed surfaces of the pads 124, 124, ... Formed in the outermost layer of the finally obtained multilayer wiring board are also formed into uneven surfaces, and when the semiconductor element 120 is mounted, the pads 124, 124 ... The pads 124 may not come into contact with each other to cause poor contact, and the reliability of the multilayer wiring board is degraded. Moreover, the thickness of the insulating layer 204 is required to be thin so as to reduce the impedance of the finally obtained multilayer wiring board, but as the thickness of the insulating layer 204 is made thinner, the resin substrate 102 is reduced. Wiring patterns 104, 10
The portions of the insulating layer 204 corresponding to 4 ...

When the sheet material 200 is used, it is necessary to apply a release agent to the PET film layer 202 so that the PET film layer 202 of the sheet material 200 thermocompression-bonded to the resin substrate 102 can be easily peeled off. Therefore, the manufacturing cost of the sheet material 200 is increased, and the manufacturing cost of the finally obtained multilayer wiring board is also increased. Therefore, an object of the present invention is to form a flat surface on an insulating layer formed by thermocompression bonding a wiring board sheet material made of an electrically insulating resin on the wiring pattern formation surface of a resin board on which a wiring pattern is formed. (EN) Provided is a wiring board sheet material, and a multilayer wiring board on which a wiring pattern including a pad connected to an electrode terminal or the like of a semiconductor element formed in the outermost layer can be formed on a flat surface.

[0006]

Means for Solving the Problems First of all, the inventors of the present invention, when using the conventional sheet material 200, cause the surface of the resin layer 204 formed on the wiring pattern forming surface of the resin substrate 102 to be an uneven surface. The PET film layer 202 was softened during thermocompression bonding and the resin substrate 1
It was found that the deformation was due to the shape of the wiring patterns 104, 104 ...
Therefore, in order to solve the above problems, the sheet material 200
The present invention has been achieved as a result of studying that it is effective to use a film layer having durability against the temperature at which the sheet material 200 is thermocompression bonded to the resin substrate 102, in place of the PET film layer 202 forming the.

That is, according to the present invention, thermocompression bonding is performed on the wiring pattern forming surface of the resin substrate on which the wiring pattern is formed,
A wiring board sheet material made of an electrically insulating resin is made of a resin that is softened or fluidized at the temperature of the thermocompression bonding, and one surface side is a thermocompression bonding film layer thermocompression bonded to the wiring pattern forming surface of the resin substrate, It is bonded to the other side of the thermocompression bonding film layer and is made of a resin whose softening or fluidizing temperature is higher than the temperature of the thermocompression bonding, and the glass transition temperature is higher than the temperature of the thermocompression bonding or glass transition point And a non-thermocompression-bonding film layer which is not included therein. Further, the present invention provides a multilayer wiring board in which a plurality of wiring patterns are laminated in multiple layers via an electrically insulating resin layer, wherein the electrically insulating resin layer is a thermocompression bonding film layer of the above-mentioned wiring board sheet material. And a non-thermocompression bonding film layer, and a via electrically connecting the wiring patterns to each other penetrates the electrically insulating resin layer formed from the thermocompression bonding film layer and the non-thermocompression bonding film layer. It is also a multilayer wiring board characterized by being formed.

In the present invention, the adhesion between the two film layers can be improved by roughening the joint surface of the non-thermocompression film layer with the thermocompression film layer. Further, by forming the non-thermocompression-bonding film layer thinner than the thermocompression-bonding film layer, the thermocompression-bonding film layer can be formed thick enough to sufficiently absorb the irregularities due to the wiring patterns and the like formed on the resin substrate. The thickness of the wiring board sheet material can be suppressed. The non-thermocompression-bonding film layer is preferably a non-thermocompression-bonding film layer which does not contain a halogen compound and exhibits self-extinguishing property, and which exhibits self-extinguishing property, particularly, a non-thermocompression film comprising polyimide, aramid or liquid crystal polymer A pressure-bonding film layer can be preferably used.
As the thermocompression bonding film layer, a thermocompression bonding film layer formed of a thermosetting resin can be preferably used, and in particular, the softening or fluidizing temperature is 100 to 150 ° C. and the curing temperature is 150 to 200. A thermocompression-bonding film layer made of a thermosetting resin at ℃ can be preferably used.

When the sheet material for a wiring board according to the present invention is thermocompression-bonded to the wiring pattern forming surface of the resin substrate, the resin forming the thermocompression-bonding film is softened or fluidized, and the sheet material for the wiring board is wired on the resin substrate. Can be bonded to the pattern formation surface. On the other hand, during such thermocompression bonding, the non-thermocompression bonding film layer having durability against the thermocompression bonding temperature is integrated with the thermocompression bonding film while maintaining a predetermined shape. Therefore, the surface of the non-thermocompression bonding film layer of the wiring board sheet material thermocompression-bonded to the wiring board is held flat enough to form a wiring pattern on the non-thermocompression bonding film layer. Therefore, the wiring pattern is formed on the non-thermocompression bonding film layer of the insulating layer formed by the wiring board sheet material thermocompression bonded to the wiring substrate, and the insulating layer formed from the thermoadhesive film layer and the non-thermocompression bonding film layer is formed. By repeating the operation of forming the penetrating via, it is possible to obtain a multilayer wiring board in which a plurality of wiring patterns are laminated in multiple layers with an insulating layer interposed therebetween. In this way, a pad with a flat exposed surface can be formed on the outermost layer of the multilayer wiring board obtained by forming a wiring pattern or the like on the surface of the non-thermocompression-bonding film layer formed on the flat surface. When mounting, the electrode terminals of the semiconductor element can be reliably brought into contact with the exposed surface of the pad.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a wiring board sheet material according to the present invention is shown in FIG. The wiring board sheet material 10 shown in FIG. 1 (hereinafter sometimes referred to as sheet material 10)
Is a thermocompression-bonding film layer 12 that is thermocompression-bonded on one side to the wiring pattern formation surface of the resin substrate when thermocompression-bonding to the wiring pattern formation surface of the resin substrate on which the wiring pattern is formed; The non-thermocompression-bonding film layer 14 is joined to the other surface side. This thermocompression bonding film layer 12
Is to be thermocompression-bonded to the wiring pattern forming surface of the resin substrate, and is therefore made of a resin that softens or fluidizes at the thermocompression-bonding temperature. As the resin forming the thermocompression-bonding film layer 12, a resin having an electric insulating property conventionally used for a multilayer wiring board, for example, an epoxy resin, a polyphenylene ether resin, an olefin resin, or the like can be used. In particular, the thermocompression bonding film layer 12 formed using a thermosetting resin is preferable because it can form an insulating layer having excellent heat resistance by thermocompression bonding to a resin substrate.
The thermosetting resin has a softening or flowing temperature of 100 to 150 ° C. and a curing temperature of 150 to 200.
By using the thermosetting resin of ℃, the thermocompression bonding treatment of the sheet material 10 can be performed using the equipment used conventionally.

The non-thermocompression-bonding film layer 14 bonded to the other surface of the thermocompression-bonding film layer 12 has a thermocompression-bonding temperature when the sheet material 10 is thermocompression-bonded to the wiring pattern forming surface of the resin substrate. On the other hand, it has heat resistance. Specifically, the non-thermocompression bonding film layer 14 is formed of a resin whose softening or fluidizing temperature is higher than the thermocompression bonding temperature, and has a glass transition point temperature higher than the thermocompression bonding temperature or a glass transition temperature. It does not have The heat resistance of the non-thermocompression-bonding film layer 14 can be measured by a differential scanning calorimeter (DSC). The measurement result is shown in FIG. In the measurement results of film A and film B shown in FIG. 2, the melting points (mp) of both films are higher than the thermocompression bonding temperature range, but the glass transition temperature (Tg) of film B is
Is lower than the thermocompression bonding temperature range. This glass transition point temperature (Tg) is a temperature at which the oriented molecular chains forming the film B easily move. Therefore, the film B having a glass transition temperature (Tg) lower than the thermocompression bonding temperature range
Is easily deformed during thermocompression bonding. On the other hand, the glass transition temperature (Tg) of film A does not exist. Therefore, in the film A, the orientation state of its molecular chains is maintained until it reaches its melting point (mp). Therefore, the melting point of film A (m.
Even if the film A is subjected to thermocompression bonding at a temperature lower than p.), the film A can retain its shape. In addition, in the film A shown in FIG. 2, the glass transition temperature (Tg) does not exist, but even if the glass transition temperature (Tg) exists, the glass transition temperature (Tg) is higher than the thermocompression bonding temperature. If it exists, it can be used for the non-thermocompression-bonding film layer 14 of the sheet material 10 shown in FIG.

The glass transition point temperature (Tg) of the non-thermocompression bonding film layer 14 varies depending on the resin to be formed and the degree of orientation of the molecular chains forming the non-thermocompression bonding film layer 14. The effect of the resin formed is also large. Therefore, the resin forming the non-thermocompression-bonding film layer 14 is not formed into a film state but is formed from a resin whose softening or fluidizing temperature is higher than the thermocompression-bonding temperature in an amorphous state. A resin having a glass transition temperature higher than the thermocompression bonding temperature or having no glass transition temperature can be preferably used. The resin is preferably polyimide, aramid or liquid crystal polymer. Non-thermocompression-bonding film layer 1 formed from such a resin
No. 4 is formed of a resin containing no halogen compound, and exhibits self-extinguishing property, so that it is possible to eliminate the fear of environmental destruction caused by the halogen compound. In the sheet material 10 shown in FIG. 1, when the non-thermocompression bonding film layer 14 and the thermocompression bonding film layer 12 are easily peeled off, the non-thermocompression bonding film layer 1
By roughening the bonding surface of No. 4 with the thermocompression bonding film layer 12 by plasma processing or the like, peeling of both layers can be effectively prevented.

Using the sheet material 10 shown in FIG. 1, a multilayer wiring board can be manufactured by the build-up method shown in FIGS. 3 and 4. In this build-up method, since the insulating layers are simultaneously formed on both sides of the core substrate, FIGS. 3 and 4 show a forming process of forming an insulating layer on one side surface of the core substrate.
The step of forming the insulating layer on the other side surface of the core substrate was omitted. In the buildup method shown in FIG. 3 and FIG.
As shown in (a) and (b), the sheet material 10 has wiring patterns 18, 18 ...
The resin substrate 16 serving as the core substrate on which is formed is superposed so as to come into contact with the wiring pattern forming surface. Through holes 20 penetrating the resin substrate 16 are formed in the resin substrate 16, and the wiring patterns 18, 18 ... Formed on both sides of the resin substrate 16 are electrically connected. In the through-hole via 20, the hollow portion of the through-hole via 20 is filled with a resin 22 so that the surface of the insulating layer formed on the through-hole via 20 is formed as flat as possible.

Further, the sheet material 10 on which the thermocompression bonding film layer 12 is pressed against the wiring pattern forming surface of the resin substrate 16 on which the wiring patterns 18, 18 ... The resin forming 12 is heated to a temperature at which it softens or fluidizes and thermocompression-bonds both [FIG. 3 (b)]. At the time of such thermocompression bonding, the thermocompression bonding film layer 1
Since the resin forming 2 softens or fluidizes, the thermocompression bonding film layer 12 is bonded while deforming along the wiring pattern forming surface of the resin substrate 16. On the other hand, since the non-thermocompression bonding film layer 14 forming the sheet material 10 is made of a resin having heat resistance against the temperature of thermocompression bonding, the deformation of the thermocompression bonding film layer 12 is affected during thermocompression bonding. The shape can be maintained without being damaged. Therefore, the non-thermocompression-bonding film layer 14 is held on the wiring pattern forming surface of the resin substrate 16 in a state where the surface thereof is held flat.
Can be glued by.

In this way, the surface of the non-thermocompression bonding film layer 14 of the sheet material 10 thermocompression bonded to the resin substrate 16 is formed into a flat surface, so that the non-thermocompression bonding film layer 14 is not peeled off to form the sheet material 10. , Laser or etching is used to form the via holes 24, 24 ... [FIG. 3 (c)].
The via hole 24 is formed so as to penetrate the non-thermocompression bonding film layer 14 and the thermocompression bonding film layer 12 of the sheet material 10, and the wiring pattern 18 formed on the resin substrate 16 is formed on the bottom surface of the via hole 24. The surface of the pad portion constituting 18 ... Is exposed. Then, a thin metal layer 26 made of copper metal is formed on the entire surface of the sheet material 10 including the bottom surface and the inner wall surface of the via hole 24 by electroless plating or sputtering [FIG. 4 (a)]. Further, a metal layer 28 made of copper metal having a predetermined thickness is formed by electrolytic copper plating using the thin metal layer 26 as a power feeding layer [FIG. 4 (b)], and the formed metal layer 28 is wired by a known method. Pattern 18 and via 30
Are formed [FIG. 4 (c)]. In this way, the core substrate 1
An insulating layer 15 composed of a non-thermocompression bonding film layer 14 and a thermocompression bonding film layer 12 on the wiring pattern 18 formed in FIG.
The wiring pattern 18 and the via 30 can be formed via the. By repeating the operations of FIGS. 3A to 3C and FIG. 4D, the multilayer wiring board 50 shown in FIG. 5 can be obtained.

A multilayer wiring board 50 shown in FIG. 4 has a through-hole via 2 penetrating a resin board 16 as a core board.
The wiring patterns 18, 18 ... Forming the upper layer portion 50a and the lower layer portion 50b formed on both surfaces of the resin substrate 16 are electrically connected by 0, 20 ,.
Each of the through-hole vias 20, 20 ... Is filled with resin 22. Also, in each of the upper layer portion 50a and the lower layer portion 50b, electrical patterns such as the wiring patterns 18, 18 ... Formed on both sides of the insulating layer 15 including the non-thermocompression bonding film layer 14 and the thermocompression bonding film layer 12 are electrically connected. Connections are vias 30 and 3 formed through each insulating layer 15.
It is made by 0 ... Further, on the uppermost layer of the upper layer portion 50a, the electrode terminals 38 of the semiconductor element 36 mounted,
.. are electrically connected to the pads 35, 35 ..
The portions other than 35 ... Are covered with the solder resist 40. On the other hand, pads 32, 32 ... On which the solder balls 34, 34 ... As external connection terminals are mounted are formed on the lowermost layer of the lower layer portion 50b.
, The lower surface of which is covered with a solder resist 40 except for the pads 32, 32.

According to the multilayer wiring board 50 shown in FIG. 5, the pads 35, 35, ... Formed on the uppermost layer of the upper layer portion 50a.
The exposed surface of can be formed into a flat surface so as to surely contact the electrode terminals 38, 38, ... When the semiconductor element 36 is mounted, and the reliability of the multilayer wiring board 50 is improved. it can. Moreover, the insulating layer 15 is the sheet material 10
The thermocompression bonding film layer 12 and the non-thermocompression bonding film layer 14 that form the
Since it is not necessary to apply a release agent between the non-thermocompression-bonding film layer 14 and the non-thermocompression bonding film layer 14, the manufacturing cost of the sheet material 10 can be reduced, and the manufacturing cost of the finally obtained multilayer wiring board 50 can be reduced. be able to. In addition, the multilayer wiring board 5
The insulating layer 15 of 0 is thinned to form the wiring patterns 18, 18 ...
Even if the thermocompression-bonding film layer 12 of the sheet material 10 is thinned in order to reduce the impedance, the surface of the non-thermocompression-bonding film layer 14 forming the surface layer of the insulating layer can be formed into a flat surface. The through-hole via 20 penetrating the core substrate 16 shown in FIGS. 1 to 6 described above is filled with the resin 22, but the resin 22 is filled with a conductive resin containing metal particles such as silver particles. May be. Thus, according to the via formed by filling the through-hole via 20 with the conductive resin, the wiring pattern can be formed on the via.

[0018]

According to the sheet material for a wiring board according to the present invention, an insulating layer having a flat surface, which is composed of a thermocompression bonding film layer and a non-thermocompression bonding film layer, which form the sheet material during the manufacture of the wiring board. Can be formed, and the reliability of the finally obtained wiring board can be improved. Furthermore, because it is not necessary to peel off some of the multiple film layers that form the sheet material,
The manufacturing cost of the sheet material can be reduced, and the manufacturing cost of the finally obtained wiring board can be reduced. In particular, according to the multilayer wiring board obtained by using the sheet material for a wiring board according to the present invention, the exposed surface of the pad that abuts the electrode terminal of the semiconductor element to be mounted surely contacts the electrode terminal of the semiconductor element. It can be contacted and its reliability can be improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a wiring board sheet material according to the present invention.

FIG. 2 is a DSC chart explaining the melting point and glass transition temperature of the resin forming the wiring board sheet material shown in FIG.

FIG. 3 is a process diagram illustrating a former step of a method for manufacturing a multilayer wiring board using the wiring board sheet material shown in FIG.

FIG. 4 is a process diagram illustrating a latter step of a method for manufacturing a multilayer wiring board using the wiring board sheet material shown in FIG.

FIG. 5 is a partial cross-sectional view illustrating an example of a multilayer wiring board formed using the wiring board sheet material shown in FIG.

FIG. 6 is a partial cross-sectional view illustrating an example of a conventional multilayer wiring board.

7A to 7C are process diagrams illustrating a method for manufacturing the multilayer wiring board shown in FIG.

FIG. 8 is a sheet material 200 used in the manufacturing method shown in FIG.
It is a partial cross-sectional view for explaining the surface shape of the insulating layer formed by.

[Explanation of symbols]

10 Wiring board sheet material 12 Thermocompression bonding film layer 14 Non-thermocompression bonding film layer 15 Insulation layer 16 core substrate (resin substrate) 18 wiring patterns 30 vias 50 multilayer wiring board

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4F100 AK01A AK01B AK47B AK49B                       AK80B BA02 BA07 DD07A                       DD07B GB43 JA04A JA04B                       JA05A JA05B JB13A JJ07B                       JL01 YY00A                 5E346 AA01 AA12 AA15 AA38 AA43                       BB01 BB16 CC08 CC09 CC10                       CC12 CC31 DD02 DD15 DD22                       EE33 EE35 EE38 FF04 GG02                       GG17 GG27 GG28 HH11

Claims (7)

[Claims] 1. A wiring board sheet material made of an electrically insulating resin, which is thermocompression bonded to a wiring pattern forming surface of a resin board on which a wiring pattern is formed, is formed from a resin that softens or fluidizes at the temperature of the thermocompression bonding. Consists of
A thermocompression bonding film layer whose one surface side is thermocompression bonded to the wiring pattern forming surface of the resin substrate, and a temperature of softening or fluidizing that is joined to the other surface side of the thermocompression bonding film layer is higher than the temperature of the thermocompression bonding. A sheet material for a wiring board, comprising a resin and a non-thermocompression bonding film layer having a glass transition temperature higher than the thermocompression bonding temperature or having no glass transition temperature. 2. The sheet material for a wiring board according to claim 1, wherein the joint surface of the non-thermocompression bonding film layer with the thermocompression bonding film layer is roughened. 3. The sheet material for a wiring board according to claim 1, wherein the non-thermocompression bonding film layer is formed thinner than the thermocompression bonding film layer. 4. The wiring board according to claim 1, wherein the non-thermocompression bonding film layer is a self-extinguishing non-thermocompression bonding film layer formed of a resin containing no halogen compound. Sheet material. 5. The wiring board sheet material according to claim 1, wherein the non-thermocompression-bonding film layer is formed of polyimide, aramid, or liquid crystal polymer. 6. The thermocompression bonding film layer is formed from a thermosetting resin, and the thermosetting resin has a softening or fluidizing temperature of 100 to 150 ° C. and a curing temperature of 150 to 2
It is 00 degreeC, The sheet material for wiring boards as described in any one of Claims 1-5. 7. A multilayer wiring board in which a plurality of wiring patterns are laminated in multiple layers via an electrically insulating resin layer, wherein the electrically insulating resin layer is thermocompression bonded to the wiring board sheet material according to claim 1. A via formed from a film layer and a non-thermocompression bonding film layer, electrically connecting the wiring patterns to each other,
A multilayer wiring board formed by penetrating an electrically insulating resin layer formed of the thermocompression bonding film layer and the non-thermocompression bonding film layer.